Composites may be fabricated with thermoset plastics such as epoxies, polyurethanes, and silicones. Epoxies may be produced by reacting an epoxy resin and a hardener. Polyurethane polymers can be formed by reacting an isocyanate with a polyol. Silicones may comprise polymerized siloxanes with organic side groups.
Carbon nanotubes (CNTs) and graphene have been used to reinforce thermoset plastics like epoxies, polyurethanes, silicones, and other resins and polymers. CNTs, functionalized CNTs (or hybrid CNTs, denoted HNTs), graphene, and functionalized graphene may collectively be referred to as hybrid graphitic materials (HGMs). These HGMs can be incorporated into any of the epoxy components such as the epoxy resin and hardener. HGMs may also be incorporated into polyurethanes and silicones.
Thermoset plastics, CNTs, graphene, and HNTs may increase modules and toughness, but elasticity may be preferred for certain plastic composites. In order to increase elasticity, siloxane may be added. Siloxane backbone may be coiled, and it can be covered by alkyl or aryl groups in silicones. Thus, silicones can be very flexible and hydrophobic. Hydrophobicity can be increased by functionalization with groups such as fluorinated alkyl or aryl groups.
Numerous functionalization methods for the CNTs have been developed. These include nitric acid/sulfuric acid oxidation of the CNTs, aryl radical addition to the CNTs, ball milling induces addition of amines and sulfides into the CNTs, butyl lithium activated coupling to alkyl halides, and ultrasonic vibration assisted addition of many reagents, including amines, and epoxies. Improving mechanochemical reactions, such as mechanical or ultrasound cutting, may induce chemical reactions of the CNTs.
An anticorrosive coating may contain sacrificial metal particles, such as zinc particles. The concentration of the particles may exceed the percolation limit, which is about 30% for spherical particles. High concentration of these particles can reduce the integrity of the coating, especially if the particles are not chemically bound with the polymer. Anticorrosive coatings may use sacrificial metal particles that are electrically connected with a coated metal surface through a CNT or graphene network. Using the CNT or graphene network may require less sacrificial metal particles within an anticorrosive coating. Additionally, the graphitic material may be coated with a metal layer. The metal layer may be comprised of nanoparticles or microparticles. The metal particles may be coated with a thin oxide layer unless the graphitic material is coated in the absence of oxygen. With the nanoparticles, the oxide layer can be a relatively large part of the particle. The oxide layer may also be a large portion for a metal coating around a CNT. Besides metallic particles, the particles may also be ceramic.